HELP! Chroloris and Necrosis growing!

[andarilhoestelar]

Hello growers!

Disclaimer: I would like to say that I am a complete beginner with almost no experience growing Cannabis.

This plant was put in 1L Airpot (with Biobizz Light Mix soil) after seed germination and she was going very well for around 3-4 weeks.
I think I have overwatered her and decided to make a transplant to a bigger 9L Airpot with Biobizz All Mix soil.
I have noticed some tip burns and I guess it happened because All Mix has some nutrients in the composition.
The plant has developed reasonably well until it was overwatered again
She stayed bad for more than one week and slowly recovered, but with a symptom: some lower leaves were having initially a bit of chlorosis and then necrosis.
I have decided to feed the plant for the first time with 1/3 of the recommended amount of fertilisers ((Biobizz Grow, Biobizz Bloom and Biobizz Top-max).
The plant started to have chlorosis and necrosis in other leaves (older ones) after some days but I am not sure if the cause was lack or excess of nutrients.
I didn't give any more fertilisers but the situation is getting worse and worse. I did a lot of research but could not get to a conclusion by myself about the cause and how to solve the problem. If I don't fix the problems it will evolve and the plant may die but if I handle in a wrong way I feel I can also kill the plant.
What should I do? Heeeelp!

Notes: I water the plant every second day only with around 0,5L of water at pH 6.2 - 6.8. The environment is kind of stable with humidity around 50% and temperature around 19C.
The plant has now 57 days.

Thanks for any input.

[Farmbuck]

19C during lights on ? If so bring it a few more degrees. I feel you may overwatered also. Reduce your water for a few days.

[andarilhoestelar]

I would say it can get 17c with lights off and 23c with lights on. But most of the time is around 19-20c
The grow box is not too much isolated from the outside and for that reason I have no much control over the temperature.

It was much worse before (very droopy), but yeah, not 100% recovered.
About watering, I am using a kitchen scale to literally weight the pot.
When the weight is around 3,2kg I water it to 3,7kg and wait until it gets 3.2kg again.
I will also buy a soil meter so I can be sure about the moisture some cm down.

[Rwise]

Loose the soil meter, it will cause problems at some time. Better to lift the pot and feel when it needs water.
Your temps are a bit low, they may purple.
From here it looks like a root zone or PH issue, hit the link at the top of this page "Plant Problems"

[andarilhoestelar]

Hey Rwise, thanks for the answer!
What do you mean with "loose the soil meter"? Not to use the kitchen scale?
Is it a good idea to use a soil moisture meter and a soil PH meter?
Looking at the "Plant Problems" it looks like a Calcium deficiency, but not sure
It it's a problem in the root zone, transplanting to a bigger pot would help somehow?

[Rwise]

I will also buy a soil meter so I can be sure about the moisture some cm down.

These will eventually cause problems just as it did for me.
"Root Zone" is another way to say PH problem, almost all deficiencies are PH issues. Which makes the PH the first thing to check.
Transplanting can help if it corrects the issue.